The central auditory system exhibits a remarkable ability to extract information from the limited representation of the acoustic environment provided by the auditory nerve. The first central processing of this information occurs in the cochlear nucleus, where sensory information is transformed and reorganized into a set of parallel ascending pathways that each emphasizes different features of the acoustic environment. While many mechanisms are involved in these transformations in the ventral cochlear nucleus (VCN), one of the most critical elements is the differential ion channel expression among the various classes of neurons. In the first aim, the hypothesis to be tested is that the potassium channel genes Kv1.1 and Kv1.2 are critical components of the channels that form the low-threshold potassium current in bushy cells. The morphological-physiological correlation will be established between K+ channel expression and cell types at two levels: the membrane conductances in the somatic membrane and the patterns of mRNA expression for selected subsets of K+ channels. In the second aim the hypothesis to be examined is that sodium channels in VCN neurons are specialized to enhance the precise timing of action potentials and to produce high discharge rates. These experiments will lead directly to biophysically detailed neural models of sensory processing by VN neurons, and will be used to provide predictions regarding the capabilities of the first stage of central processing in both normal and damaged auditory systems.